feat: implement loading of older messages functionality

[SinghaAnirban005]

Brief Title

Implement Loading of Older Messages Feature

Acceptance Criteria fulfillment

• Implemented functionality to load older messages on scroll
• Created backend endpoint getOlderMessages to fetch older messages.
• Ensured UI displays older messages smoothly when loaded.

Fixes #793

Video/Screenshots

EmbeddedChat._.Simple.-.Simple.Storybook.-.Personal.-.Microsoft.Edge.2025-01-06.02-18-31.mp4

PR Test Details

Note: The PR will be ready for live testing at https://rocketchat.github.io/EmbeddedChat/pulls/pr-810 after approval. Contributors are requested to replace <pr_number> with the actual PR number.

[abirc8010]

Hey @SinghaAnirban005, could you please check something? In your workspace, try reducing the number of messages returned by the API (say 4 or 6 maybe for testing purpose). After that, try loading the messages again. Are the older messages being fetched correctly ? I noticed that you're increasing the offset by 50 everytime.

[SinghaAnirban005]

The endpoint responds back with around 50 as limit so having offset as 4 or 6 would not make sense . In every batch around 50 is limit so is the offset accordingly, and yes it does fetch all messages .

[abirc8010]

No no I am not telling you to set offset increment to 4 or 6. You said the api returns in batches of 50 but you can modify this value from your workspace right? I am telling you to try reducing this value.

[SinghaAnirban005]

Well , got it ...
i believe then hardcoding the offset value isn't a very good thing , will make changes
Thank You !

[Spiral-Memory]

Hey @SinghaAnirban005
This is an awesome PR and a very much needed addition.
Thanks a lot for this!

Just one request: the alignment isn’t very good. Can you move the loader a bit higher, farther to the date? Right now, it looks too close.

Also, how did it fetch older messages before? Was there no such functionality earlier?
I saw in your issue that you mentioned some manual trigger—what’s that?

[SinghaAnirban005]

Hey @SinghaAnirban005 This is an awesome PR and a very much needed addition. Thanks a lot for this!

Just one request: the alignment isn’t very good. Can you move the loader a bit higher, farther to the date? Right now, it looks too close.

Also, how did it fetch older messages before? Was there no such functionality earlier? I saw in your issue that you mentioned some manual trigger—what’s that?

There was no provision to fetch older messages earlier
Regarding the manual trigger thing i believe it was related to rendering of emojis on the chatInput section where i had to manually trigger a function so that emojis could be seen in visual manner

[SinghaAnirban005]

@Spiral-Memory
After changes

EmbeddedChat._.Simple.-.Simple.Storybook.-.Personal.-.Microsoft.Edge.2025-01-11.19-20-03.mp4